Image processing apparatus and image processing method

ABSTRACT

There is provided an image processing apparatus including a converting unit for converting a level range of an input image signal into a predetermined level range, and an outputting unit for outputting the converted image signal and first identification information which indicates the predetermined level range, the first identification information being correlated with the converted image signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a CONTINUATION of prior U.S. patent application Ser.No. 11/151,992 filed Jun. 14, 2005, which claims priority from JapanesePatent Application No. 2004-185977, filed Jun. 24, 2004, the disclosuresof which are hereby incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to digital signal processing for amultiple-valued image signal.

2. Description of the Related Art

In image transmission including a recording and reproducing of imagedata, the image data is compression-encoded in order to reduce theamount of data. The image data that is compressed-encoded may have adynamic range that is different.

For example, a digital transmission specification “REC656” is prescribedto use a range of 16-235 in a range of 0-255 using 8-bit image data.That is, in the digital transmission specification, a black level is setto 16 and a white level is set to 235. The 8-bit image data which is notbased on this transmission specification has the dynamic range from 0 to255. Also, an image input apparatus can set up the dynamic range using amanual. The image data which has various dynamic ranges as describedabove can exist together.

In cases where compression encoding is performed for the image data,without taking the dynamic range of the image data into consideration,image quality deterioration, such as a reduction of contrast and anartifact where should be true black, has occurred by the compressionencoding.

The following image processing has been proposed as a method of solvingthe above-described problem. The density histogram by the pixel value ofimage data is calculated and the pixel values according to white andblack are predicted by the histogram. A dynamic range is determined fromthe pixel values and the parameter of encoding is set up based on thedynamic range. Since each image does not always have both the whitelevel and the black level in a screen by the above-described method, itis difficult to determine a suitable encoding parameter certainly andstably. The apparatus needs to calculate the density histogram and thereis a problem that there are large loads on hardware (such as a memoryand a computing element) and software.

Also, in order to correct the difference of the display propertiesbetween different display apparatuses, the encoding apparatus which cancorrect the difference of the dynamic range and gamma characteristicsbetween display apparatuses has been proposed. In the above-describedapparatus, the image data with which the dynamic ranges are differentcannot be handled simultaneously.

Recently, use of photographing apparatuses that can select still imagerecording and moving image recording has spread. The dynamic range ofimage data is different in the still image recording and the movingimage recording. If the still image and the moving image areconcatenated and edited, the image quality deterioration, such as thereduction of contrast or over-contrast (it means that the image is toobright or too dark), is caused from the difference of the dynamic range.Thus, using the above-described apparatuses and methods, it is difficultto obtain a good quality edit of an image.

SUMMARY OF THE INVENTION

In view of the above problem in the conventional art, the presentinvention provides an image processing apparatus and an image processingmethod which makes high quality image processing possible for the imagedata of any dynamic ranges.

In accordance with an aspect of the present invention, an imageprocessing apparatus includes: a converting unit arranged to convert alevel range of an input image signal into a predetermined level range;and an outputting unit arranged to output the converted image signal andfirst identification information which indicates the predetermined levelrange, the first identification information being correlated with theconverted image signal.

In accordance with another aspect of the present invention, an imageprocessing method includes the following steps: converting a level rangeof an input image signal into a predetermined level range; andoutputting the converted image signal and first identificationinformation which indicates the predetermined level range, the firstidentification information being correlated with the converted imagesignal.

Further features and advantages of the present invention will becomeapparent from the following description of exemplary embodiments (withreference to the attached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an image processing apparatus in a firstembodiment of the present invention.

FIG. 2 illustrate illustrates a table of an example of an ID, and aminimum level value and a maximum level value corresponding to the ID.

FIG. 3 illustrates a transition of a level range according to aprocessing procedure in a first embodiment.

FIGS. 4A and 4B illustrate an example of a conversion characteristic ina first embodiment.

FIGS. 5A, 5B and 5C illustrate a transition of a level range of an imagesignal.

FIG. 6 is a flowchart illustrating a procedure of an encoding process ina first embodiment.

FIG. 7 is a flowchart illustrating a procedure of a decoding process ina first embodiment.

FIG. 8 is a block diagram of an image processing apparatus in a secondembodiment of the present invention.

FIG. 9 illustrates a transition of a level range according to aprocessing procedure in a second embodiment.

FIG. 10 is a flowchart illustrating a procedure of an encoding processin a second embodiment.

FIG. 11 is a flowchart illustrating a procedure of a decoding process ina second embodiment.

DESCRIPTION OF THE EMBODIMENTS First Embodiment

FIG. 1 is a block diagram of an image processing apparatus in a firstembodiment of the present invention.

The image signal which should be recorded on recording media 106 isinput into signal processing unit 101 from an external apparatus. Thesignal processing unit 101 performs a color conversion and filtering onthe image signal. Known general color conversion and filteringtechniques can be used and are thus not described herein. The imagesignal processed by the signal processing unit 101 is input into a firstID detecting/converting unit 102. The first ID detecting/converting unit102 detects ID information which indicates the level range of the imagesignal processed by the signal processing unit 101. A level range of theimage signal is determined based on the ID information. Then, the levelrange of the image signal is converted so that it may become the levelrange corresponding to a coding processing. The image signal which isinput into the first ID detecting/converting unit 102 includes the IDinformation.

FIG. 2 illustrates an exemplary ID information table which includes IDinformation, and a minimum level value and a maximum level valuecorresponding to the ID information. In the example shown in FIG. 2, theimage signal is expressed by an 8-bit value. Further, in the exampleshown in FIG. 2: when the ID is 0, the minimum level value is 0 and themaximum level value is 255; when the ID is 1, the minimum level value is10 and the maximum level value is 240, etc. In this embodiment, the minof a luminance value indicates a black level, and the max of theluminance value indicates a white level. Thus, in this example, when theID is 1, the black level is 10 and the white level is 240.

Referring again to FIG. 1, the image signal into which a level range wasconverted by the first ID detecting/converting unit 102 is input into anencoder 103. The encoder 103 encodes the image signal output from thefirst ID detecting/converting unit 102. A first ID adding unit 104 addsthe ID information which indicates the level range converted by thefirst ID detecting/converting unit 102 to the image signal encoded bythe encoder 103. For example, in cases where the first IDdetecting/converting unit 102 converts the level range of the imagesignal into the level range of ID=0 (min=0 and max=255), the first IDadding unit 104 adds the ID information which indicates ID=0, asidentification information of the level range, to the image signalencoded by the encoder 103.

A media recording unit 105 processes the image signal (including the IDinformation), which is output from the first ID adding unit 104, using arecording format corresponding to a recording medium 106 (such as anoptical disk), and records the processed image signal on the recordingmedium 106. That is, the processed image signal including the IDinformation is recorded on the recording medium.

A reproducing operation is described next. A media reproducing unit 107reproduces the image signal recorded on the recording medium 106, andoutputs the image signal to a decoder 108. The decoder 108 decodes thereproduced image signal. The decoded image signal is input into a secondID detecting/converting unit 109.

The second ID detecting/converting unit 109 detects the ID informationwhich indicates the level range of the decoded image signal andconverts, based on the detected ID information, the level range of thedecoded image signal into the level range which suits a display unit111.

The image signal in which the level range is converted by the second IDdetecting/converting unit 109 is input into a second ID adding unit 110.The second ID adding unit 110 adds the ID information equivalent to thelevel range converted by the second ID detecting/converting unit 109 tothe image signal, and outputs it to the display unit 111. For example,in cases where the second ID detecting/converting unit 109 converts thelevel range into the level range of ID=2 (min=15, max=250), the secondID adding unit 110 adds the ID information which indicates the ID=2 tothe image signal. Since the image signal of the level range optimizedfor the display unit 111 is input into the display unit 111, a highquality image is displayed on the display unit 111.

FIG. 3 illustrates a transition of a level range according to aprocessing procedure in a first embodiment. In this example, the firstID detecting/converting unit 102 converts an input level range of ID=1(min=10, max=240) into the level range of ID=0 (min=0, max=255). FIG. 4Aillustrates an example of the conversion characteristic of the first IDdetecting/converting unit 102. The first ID detecting/converting unit102 converts the input values of 10 to 240 into the values of 0 to 255according to the conversion characteristic of FIG. 4A, and outputs theconverted image signal. The conversion process may be realized, forexample, by a look-up table, or by math processing. Processing is thenperformed with the optimal dynamic range. The processing performed usingthe optimal dynamic range includes: an encoding process by the encoder103; a recording/reproducing process by the media recording unit 105,recording medium 106 and the media reproducing unit 107; and a decodingprocess of the decoder 108. The second ID detecting/converting unit 109converts the level range of the reproduced image signal into the levelrange (ID=2, min=15, max=250) of the display unit 111. FIG. 4Billustrates an example of the conversion characteristic of the second IDdetecting/converting unit 109. The second ID detecting/converting unit109 converts the input values of 0 to 255 into the values of 15 to 250according to the conversion characteristic of FIG. 4B, and outputs theconverted image signal. The conversion process may be realized, forexample, by a look-up table, or by math processing. By the aboveprocessing, the high quality image can be displayed in the display unit111.

Another effect of this embodiment is explained below using FIGS. 5A, 5Band 5C. FIGS. 5A, 5B and 5C illustrate a transition of the level rangeof the image signal, in cases where several scenes from which the levelrange of an image signal is different are concatenated in editing. InFIGS. 5A, 5B and 5C, a horizontal axis illustrates a time-axis and avertical axis illustrates a level. FIG. 5A illustrates the transition ofthe level range of an input image signal. FIG. 5B illustrates thetransition of the level range of encoding an image signal. FIG. 5Cillustrates the transition of the level range of an output image signal.

In FIG. 5A, a scene 1 has ID=1, a scene 2 has ID=0, a scene 3 has ID=2,a scene 4 has ID=0 and a scene 5 has ID=1. In cases where the imagesignal consists of scenes which have a different level range, such as isshown in FIG. 5, encoding and decoding the image signal as it is causesimage quality deterioration, such as the reduction of contrast orover-contrast. In order to prevent the above-mentioned imagedeterioration problem, before encoding, the level range of the inputimage signal is converted into a constant range so that the level rangeof the encoded signal may become constant. Thus, as illustrated in FIG.5B, the level range becomes the same on each scene, and the encodingprocess, the recording process, the reproducing process and the decodingprocess can be performed without causing a difference in the imagequality.

After decoding, as illustrated in FIG. 5C, the level range of a decodedimage signal is converted according to output equipment (in thisembodiment, it is the display unit 111).

An encoding process of the first embodiment is described next withreference to FIG. 6.

FIG. 6 is a flowchart illustrating a procedure of the encoding processin the first embodiment.

In step S601, the ID information (in the following, referred to as“inputting ID information”) which indicates the level range informationof the input image signal is acquired by the first IDdetecting/converting unit 102, and the processing proceeds to step S602.The ID information is included in a header portion of the input imagesignal. That is, the ID information has been added to the input imagesignal. In step S602, the ID information (in the following, referred toas “encoding ID information”) which indicates the level range of theimage signal when encoding is acquired, and the processing progresses tostep S603. The encoding ID information is pre-stored in a work memory(not shown). In step S603, the inputting ID information is compared withthe encoding ID information. If the inputting ID information matches thecoding ID information (yes in step S603), the processing proceeds tostep S606. If the inputting ID information does not match the encodingID information (no in step S603), the processing proceeds to step S604.

In step S604, the conversion characteristic for converting the levelrange of the inputting ID information to the level range of the encodingID information is set, and the processing proceeds to step S605. Theconversion characteristic may be set by a look-up table, or by mathprocessing. In the case of a look-up table, the look-up table should bepre-stored in the work memory. In step S605, a converting process of thelevel range of the inputting image signal is performed according to theconversion characteristic set in step S604, and the processing proceedsto step S606. The level range of the image signal of all scenes turnsinto the level range corresponding to the encoding process in step S605(see FIG. 5B).

In step S606, the converted image signal is encoded by a predeterminedcompression-encoding method (e.g., MPEG (Moving Picture ExpertsGroup)-2, Motion JPEG (Joint Photographic Coding Experts Group) etc.),and the processing proceeds to step S607. In step S607, as for theencoded image signal, the ID information (in the following, referred toas “decoding ID information” is the same information as the encoding IDinformation) is added to the header portion of the encoded image signal,and the processing then ends. That is, in step S607, the encoded imagesignal is output in correlation with the decoding ID information.

Thus, according to the above-described processing, it is possible toperform a high quality encoding process, without causing image qualitydeterioration.

A decoding process of the first embodiment is described next withreference to FIG. 7.

FIG. 7 is a flowchart illustrating a procedure of the decoding processin the first embodiment.

In step S701, the image signal reproduced by the media reproducing unit107 is decoded by the decoder 108, and the processing proceeds to stepS702. In step S702, the decoding ID information is acquired by thesecond ID detecting/converting unit 109, and the processing proceeds tostep S703. In step S703, the ID information (in the following, referredto as “outputting ID information”) which indicates the level range ofthe image signal when outputting to the display unit 111 is acquired,and the processing proceeds to step S704. The outputting ID informationis pre-stored in the work memory (not shown).

In step S704, the decoding ID information is compared with theoutputting ID information. If the decoding ID information matches theoutputting ID information (yes in step S704), the processing proceeds tostep S707. If the decoding ID information does not match the outputtingID information (no in step S704), the processing proceeds to step S705.

In step S705, the conversion characteristic for converting the levelrange of the decoding ID information to the level range of theoutputting ID information is set, and the processing proceeds to stepS706. The conversion characteristic may be set by a look-up table, ormath processing. If a look-up table is used, the look-up table should bestored in the work memory beforehand. In step S706, a converting processof a level range of the decoded image signal is performed based on theconversion characteristic set in step S705, and the processing proceedsto step S707. The level range of the image signal of all scenes turnsinto the level range corresponding to the display unit 111 by theprocessing of step S707 (see FIG. 5C).

In step S707, as for the converted image signal, the ID information (inthe following, referred to as “outputting ID information”) is added tothe header portion of the converted image signal, and the processingthen ends. That is, in step S707, the converted image signal is outputin correlation with the outputting ID information.

Thus, with the above-described processing, it is possible to have highquality outputting processing, without causing image qualitydeterioration.

In this embodiment, although the image signal is expressed in anunsigned 8-bit data format, the present invention is not limited to sucha data length and data representation form. The data format whichexpresses a zero level with a mid-value may be sufficient as the imagesignal. In a system that needs gamma processing, a gamma correction maybe simultaneously performed, at the time of the conversion processing ofthe level range, in consideration of a gamma characteristic. Also, inthis embodiment, although there were three kinds of ID information, thepresent invention is not limited to this.

Also, in cases where the level range of the moving image signal is apredetermined constant level range and the level range of the stillimage signal is a predetermined constant level range, the first IDdetecting/converting unit 102 may be made to correspond with a sourceidentification flag for discriminating the moving image signal and thestill image signal instead of the ID information.

In FIG. 1, for circuit reduction, the first ID detecting/converting unit102 and the second ID detecting/converting unit 109, and the first IDadding unit and the second ID adding unit may include common circuits.

Second Embodiment

A second embodiment of the present invention is described below.

FIG. 8 is a block diagram of an image processing apparatus in a secondembodiment of the present invention. Components of the second embodiment(shown in FIG. 8) that have the same function as components of the firstembodiment (shown in FIG. 1 and described above) have the same referencenumber.

In the embodiment illustrated in FIG. 1, the level range of the imagesignal is discriminated by the ID information (described above). In thisembodiment, the level information which indicates the white level andblack level of the image signal is added to the image signal, and thelevel information is transmitted. The level range of the image signal isdetermined by the level information.

The image signal that should be recorded on recording medium 106 isinput into signal processing unit 101 from an external apparatus. Asdescribed above, the signal processing unit 101 performs a colorconversion (e.g., a publicly known general color conversion) process anda filtering (e.g., a publicly known general filtering) process to theimage signal. The image signal processed by the signal processing unit101 is input into a first level range converting unit 801. The firstlevel range converting unit 801 detects level range information whichindicates the white level range and black level range of the imagesignal processed by the signal processing unit 101. A level range of theimage signal is determined based on the level range information. Then,the level range of the image signal is converted so that it may becomethe level range corresponding to a coding processing.

The image signal into which a level range was converted by the firstlevel range converting unit 801 is input into an encoder 103. Theencoder 103 encodes the image signal output from the first level rangeconverting unit 801. A first level range information adding unit 802adds the level range information which indicates the white level andblack level converted by the first level range converting unit 801 tothe image signal encoded by the encoder 103. For example, in cases wherethe first level range converting unit 801 converts a level range of theimage signal into the black level=0 and white level=255, the first levelrange information adding unit 802 adds the level range information whichindicates the black level=0 and white level=255, into the image signalencoded by the encoder 103.

A media recording unit 105 processes the image signal (including the IDinformation), which is output from the first level range informationadding unit 802, to a recording format corresponding to a recordingmedia 106 (such as an optical disk), and records the processed imagesignal on the recording medium 106. That is, the processed image signalis recorded on the recording medium 106 in correlation with the firstlevel range information.

A reproducing operation is explained next. A media reproducing unit 107reproduces the image signal recorded on the recording media 106, andoutputs the image signal to a decoder 108. The decoder 108 decodes thereproduced image signal. The decoded image signal is input into a secondlevel range converting unit 803.

The second level range converting unit 803 detects the level rangeinformation which indicates the white level and black level of thedecoded image signal and converts, based on the detected level rangeinformation, the level range of the decoded image signal into the levelrange which suits a display unit 111.

The image signal in which the level range is converted by the secondlevel range converting unit 803 is input into a second level rangeinformation adding unit 804. The second level range information addingunit 804 adds the ID information equivalent to the level range convertedby the second level range converting unit 803 to the image signal, andoutputs it to a display unit 111. For example, in cases where the secondlevel range converting unit 803 converts the level range into the blacklevel=15 and white level=250, the second level range information addingunit 804 adds the level range information which indicates the blacklevel=15 and white level=250 to the image signal. Since the image signalof the level range optimized for the display unit 111 is input into thedisplay unit 111, a high quality image is displayed on the display unit111.

FIG. 9 illustrates a transition of a level range according to aprocessing procedure in the second embodiment. In this example, thefirst level range converting unit 801 converts an inputting level rangeof the black level=10 and white level=240 into the level range of theblack level=0 and white level=255. This conversion process is realizedby the same technique as the above-described first embodiment. Then, anencoding process of the encoder 103; and a recording/reproducing processby the media recording unit 105, recording media 106 and mediareproducing unit 107; and a decoding process of the decoder 108 areperformed using the optimal dynamic range. The second level rangeconverting unit 803 converts the level range of the reproduced imagesignal into the level range (the black level=15 and white level=250) ofthe display unit 111. By the above processing, the high quality imagecan be displayed using the display unit 111.

This embodiment can output high quality images without causing thedifference of the image quality (e.g., the reduction of contrast orover-contrast) for the image signal of a plurality of scenes from whichthe level range of an image signal is different where the processingincludes concatenation editing.

An encoding process of the second embodiment is described next withreference to the flowchart shown in FIG. 10.

In step S1001, the level range information (in the following, referredto as “inputting level range information”) which indicates the whitelevel and black level of the input image signal is acquired by the firstlevel range converting unit 801, and the processing proceeds to stepS1002. The level range information is stored in a header portion of theinput image signal. In step S1002, the level range information (in thefollowing, referred to as “encoding level range information”) whichindicates the white level and black level of the image signal whenencoding is acquired, and the processing proceeds to step S1003. Theencoding level range information is pre-stored in a work memory (notshown). In step S1003, the inputting level range information is comparedwith the encoding level range information. If the inputting level rangeinformation matches the coding level range information (yes in stepS1003), the processing proceeds to step S1006. If the inputting levelrange information does not match the encoding level range information(no in step S1003), the processing proceeds to step S1004.

In step S1004, the conversion characteristic for converting the levelrange of the inputting level range information to the level range of theencoding level range information is set, and the processing proceeds tostep S1005. The conversion characteristic may be set up by a look-uptable, or by math processing. In the case of a look-up table, thelook-up table should be pre-stored in the work memory. In step S1005, aconverting process of the level range of the inputting image signal isperformed according to the conversion characteristic set in step S1004,and the processing proceeds to step S1006. The level range of the imagesignal of all scenes turns into the level range corresponding to theencoding process in step S1005.

In step S1006, the converted image signal is encoded by a predeterminedcompression-encoding method (e.g., MPEG-2, Motion JPEG, etc.), and theprocessing proceeds to step S1007. In step S1007, as for the encodedimage signal, the level range information (in the following, referred toas “decoding level range information” and the decoding level rangeinformation is the same information as the encoding level rangeinformation) is added to the header portion of the encoded image signal,and the processing then ends. That is, in step S1007, the encoded imagesignal is output in correlation with the decoding level rangeinformation.

It is possible to have high quality encoding processing, without causingthe image quality deterioration with the above-described processing.

A decoding process of the second embodiment is described below withreference to the flowchart shown in FIG. 11.

In step S1101, the image signal reproduced by the media reproducing unit107 is decoded by the decoder 108, and the processing proceeds to stepS1102. In step S1102, the decoding level range information is acquiredby the second level range converting unit 803, and the processingproceeds to step S1103. In step S1103, the level range information (inthe following, it is referred to as “outputting level rangeinformation”) which indicates the level range of the image signal whenoutputting to the display unit 111 is acquired, and the processingproceeds to step S1104. The outputting level range information ispre-stored in the work memory (not shown).

In step S1104, the decoding level range information is compared with theoutputting level range information. If the decoding level rangeinformation matches the outputting level range information (yes in stepS1104), the processing proceeds to step S1107. If the decoding levelrange information does not match the coding level range information (noin step S1104), the processing proceeds to step S1105.

In step S1105, the conversion characteristic for converting the levelrange of the decoding level range information to the level range of theoutputting level range information is set, and the processing proceedsto step S1106. The conversion characteristic may be set by a look-uptable, or math processing. If a look-up table is used, the look-up tableshould be pre-stored in the work memory. In step S1106, a convertingprocess of the level range of the decoded image signal is performedbased on the conversion characteristic set in step S1105, and theprocessing proceeds to step S1107. The level range of the image signalof all scenes turns into the level range corresponding to the displayunit 111 by the processing of step S1107.

In step S1107, as for the converted image signal, the level rangeinformation (in the following, it is referred to as “outputting levelrange information”) is added to the header portion of the convertedimage signal, and the processing then ends. That is, in step S1107, theconverted image signal is output in correlation with the outputtinglevel range information.

It is possible to have high quality outputting processing, withoutcausing the image quality deterioration by the above-describedprocessing.

In this embodiment, although the image signal is expressed in anunsigned 8-bit data format, the present invention is not limited to sucha data length and data representation form. The data format whichexpresses a zero level with a mid-level value may be sufficient as theimage signal. In a system that needs gamma processing, a gammacorrection may be simultaneously performed, at the time of theconversion processing of the level range, in consideration of a gammacharacteristic. Also, in this embodiment, although there were threekinds of ID information, the present invention is not limited to this.

This embodiment illustrates the level range information of the imagesignal by using the information of the white level and black level.However, the present invention is not limited to the white level andblack level. The other information may be sufficient as long as it isinformation that can determine a level range of an image signal (e.g.,information which indicates the white level and a mid-level between thewhite level and black level, or the black level and the mid-level).

Other Embodiments

In the above-described embodiment, although decoding process isperformed after coding, this invention can be also applied in caseswhere coding process is performed after decoding (e.g., at the time ofedit of the encoding data).

A storage medium storing program code may be provided for performing theabove-described processes to an image sensing system or apparatus,reading the program code, by a CPU (central processing unit) or MPU(micro processing unit) of the image sensing system or apparatus, fromthe storage medium, then executing the program.

In this case, the program code read from the storage medium realizes thefunctions according to the embodiments.

Further, the storage medium, such as a floppy disk, a hard disk, anoptical disk, a magneto-optical disk, a CD-ROM (compact disk-read-onlymemory), a CD-R (CD-recordable), a magnetic tape, a non-volatile typememory card, and a ROM, and a computer network, such as a LAN (localarea network) and a WAN (wide area network), can be used for providingthe program code.

Furthermore, embodiments of the invention may include an OS (operatingsystem) or the like working on the computer which perform a part orentire processes in accordance with designations of the program code andrealize functions according to the above embodiments.

Furthermore, the present invention also includes a case where, after theprogram code read from the storage medium are written in a functionexpansion card which is inserted into the image sensing system orapparatus or in a memory provided in a function expansion unit which isconnected to the image sensing system or apparatus, CPU or the likecontained in the function expansion card or unit performs a part orentire process in accordance with designations of the program code andrealizes functions of the above embodiments.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed embodiments. On the contrary, the invention isintended to cover various modifications and equivalent arrangementsincluded within the spirit and scope of the appended claims. The scopeof the following claims is to be accorded the broadest interpretation soas to encompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Laid-Open No.2004-185977, filed Jun. 24, 2004, which is hereby incorporated byreference herein.

1. A method of processing an image signal with an image processingapparatus that includes a signal processing unit, the method comprisingsteps of: receiving, at the signal processing unit, an input imagesignal to which first identification information indicative of a levelrange of the input image signal is added; detecting the firstidentification information and determining the level range of the inputimage signal; converting the level range of the input image signal intoa first predetermined level range in accordance with the firstidentification information and second identification information whichcorresponds to a level range of the image processing apparatus; addingthe second identification information to the converted image signal sothat the second identification information indicates the firstpredetermined level range of the converted image signal; and outputtingthe converted image signal and the second identification informationadded thereto, wherein the first and second identification informationinclude information indicating at least one of the level range and asource identification flag which is used by the signal processing unitwith respect to the input image signal.
 2. The method according to claim1, further comprising: encoding the converted image signal; recordingthe encoded image signal and the second identification informationoutput on a recording medium, the second identification informationbeing correlated with the encoded image signal; reproducing the encodedimage signal and the second identification information from therecording medium; decoding the reproduced image signal; converting thelevel range of the decoded image signal into a second predeterminedlevel range in accordance with third identification information; andoutputting the converted image signal of the second predetermined levelrange and the third identification information which indicates thesecond predetermined level range.
 3. A non-transitory computer readablestorage medium storing therein a computer program executable by acomputer to perform the image processing method according to claim
 1. 4.The method according to claim 1, wherein the source identification flagdiscriminates whether the input image signal corresponds to a movingimage signal or a still image signal.
 5. An image processing apparatuscomprising: an input unit arranged to receive an input image signal towhich first identification information indicative of a level range ofthe input image signal is added; a detecting unit arranged to detect thefirst identification information and determine the level range of theinput image signal; a first converting unit arranged to convert thelevel range of the input image signal into a first predetermined levelrange in accordance with the first identification information and secondidentification information which corresponds to a level range of theimage processing apparatus; an identification information adding unitarranged to add the second identification information to the convertedimage signal so that the second identification information indicates thefirst predetermined level range of the converted image signal; and afirst outputting unit arranged to output the converted image signal andthe second identification information added thereto, wherein the firstand second identification information include information indicating atleast one of the level range and a source identification flag which isused by the signal processing unit with respect to the input imagesignal.
 6. An image processing apparatus according to claim 5, furthercomprising: an encoder arranged to encode the converted image signal; arecording unit arranged to record the encoded image signal and thesecond identification information output on a recording medium, thesecond identification information being correlated with the encodedimage signal; a reproducing unit arranged to reproduce the image signaland the second identification information from the recording medium; adecoder arranged to decode the reproduced image signal; a secondconverting unit arranged to convert the level range of the decoded imagesignal into a second predetermined level range in accordance with athird identification information; and a second outputting unit arrangedto output the converted image signal converted by the second convertingunit and the third identification information which indicates the secondpredetermined level range.
 7. The apparatus according to claim 5,wherein the source identification flag discriminates whether the inputimage signal corresponds to a moving image signal or a still imagesignal.